1. Field of the Invention
Embodiments of the present invention relate to optical waveguide attachment techniques and, more particularly, to techniques for achieving a low loss large diameter fusion splice.
2. Description of the Related Art
Optical industry manufacturers have a variety of products that require attachment or splicing to optical waveguide elements having a larger diameter than typical optical fibers. For example, a thermal gratings, gain flattening filters, pressure and temperature sensors, and potentially many others type devices may be formed in large diameter optical waveguides. In order to connect such devices to optical signal processing equipment, or other such devices connected in series, optical fiber may be attached to the device. To facilitate attachment to such devices, the optical fiber may be encapsulated in a carrier or pigtail having a larger diameter.
Low-loss fusion splicing of optical fiber is a very common operation and many techniques have been developed in order to facilitate this process. For example, one common technique is to use a laser to perform splices, as disclosed in “Optical fiber splicing with a low-power CO2 laser” by Egashira and Kobayashi, Appl. Opt. 16, 1636-1638 (1977), “Monomode fibre fusion splicing with CO2 laser” by Rivoallan et. al., Electronics Letters, vol. 19, No. 2, Jan. 20, 1983, pp 54-55, and U.S. Pat. No. 5,161,207, entitled “Optical fiber circumferentially symmetric fusion splicing and progressive fire polishing.”
Such conventional techniques, however, are typically limited to fiber diameters of 400 um or less. Modifying devices utilizing these techniques to accommodate larger diameters optical waveguides (e.g., of a large diameter carrier and device that may be greater than 1 mm) would present a challenge and may not be feasible, particularly when trying to maintain uniform heating around the entire diameter of the splice area to achieve a strong splice, while also maintaining alignment of the narrow (e.g., 5 um diameter) fiber cores to minimize optical loss through the splice region. As a result, encapsulated fiber pigtails are often attached to large diameter devices via epoxy, which not only limits the heat, humidity, and corrosiveness of the environments in which the devices may be placed, but also results in optical loss if the epoxy is placed in the optical path.
Accordingly, what is needed is the capability to perform a large diameter splice (LDS), preferably using laser fusion thus reducing or eliminating many of the disadvantages associated with using epoxy.